Percussion drill



1950 J. E. FEUCHT 2,947,519

PERCUSSION DRILL Filed Sept. 11, 1957 4 Sheets-Sheet 1 s W3 INVENTORL J. E. PEI 6H7 2, 1950 J. E. FEUCHT 2,947,519

PERCUSSION DRILL Filed Spt. 11, 1957 4 Sheets-Sheet 2 "a EIQ Q Q} Q i; w QQ 52 INVENTORN J. E. F5001?- 1950 J. E. FEUCHT 2,947,519

PERCUSSION DRILL Filed Sept. 11, 1957 4 Sheets-Sheet 3 INVENTOR. J. E FEUC'HT wwtEfiha/ PERCUSSION DRILL Jacob E. Feucht, Garfield Heights, Ohio, assignor to Westinghouse Air Brake Company, Wilmer-ding, Pa., a corporation of Pennsylvania Filed Sept. 11, 1957, Ser. No. 683,408

9 Claims. (Cl. 255-4-4) This invention relatesto a fluid actuated impact tool which finds particular utility in earth drilling. I

Drill tools of this general type usually include an elongated cylinder which forms the outer casing of the drill. A piston is reciprocally mounted within the casing and forms the hammer which is actuated by fluid, such as compressed air. An anvil is also mounted in the casing for slight reciprocatory movement and has a cutting bit at its outer end while its inner end is adapted to be struck by the hammer. Drills of the type to which this invention pertains are known as down-the-hole drills. They are lowered into the hole being formed in a drill string which is suitably attached to the upper end of the casing and through which the compressed air is introduced into the drill. The compressed air passes through suitable valving in the drill to alternately force the hammer against the anvil with a sharp impact and then return the hammer to the starting position. The compressed air is discharged from the drill through apertures in the bit which causes the drillings to be blown out of the hole.

Various devices have heretofore been proposed which have rather complicated valving mechanism designed to regulate the flow of fluid through the drill in order to utilize the pressure fluid to apply a power stroke to the hammer, and then return the hammer to the starting position before the fluid is permitted to escape to clean out the drillings. The use of complicated valves not only increases the number of relatively moving parts subject to misalignment and wear, but also adds to the cost of the drill and increases the over all size, particularly the diameter, of the drill.

According to the present invention, a down-hole, fluid pressure actuated, impact drill is provided which utilizes a porting sleeve between the piston hammer and cylinder casing, resulting in a particularly compact drill that is economical to manufacture, highly versatile asto the operations it can perform and very eflicient in performing its intended functions.

Difierent types of impact blows are desirable in tools of this type. For example, some drills should deliver a hard, long stroke while in others a faster, lighter impact is desirable.

By means of this invention drills have been provided which are capable of being made from substantially the same tools and using a considerable number of common parts, the drills, however, having different operating characteristics.

Another aspect of the invention provides that the novel porting sleeve of the drill is slidable so as to increase the length of piston travel during which the compressed air is effective on the piston in delivering the power stroke. Similarly, the length of return travel of the piston during which the pressure fluid acts to return the piston, is also increased.

With the particular porting sleeve arrangement of this invention, a source of compressed air is always located closely to either end of 'the piston for instantaneously States Patent ice moving the latter in either direction as the ports are opened.

Another aspect of the invention provides that when the drill is raised slightly from its cutting position, the entire source of compressed air will automatically be directed out through the bits to blow the drillings from the hole and will be ineffective to return the hammer to the starting position. No separate or manual adjustments are required to efiect this blowout position.

These and other objects and advantages of the invention will appear hereinafter as this disclosure progresses, reference being had to the accompanying drawings in which:

Figures 1 and 2 are longitudinal cross-sectional views of a drill made in accordance with this invention, the devices of these figures being one drill; the device of Figure 2 simply being being a continuation of the 'Figure 1 de-' vice. The drill is shown here with its parts in position at the start of a power stroke;

Figures 3 and 4 are views similar to Figures 1 and 2 but show the parts at the striking point or where the hammer engages the anvil;

Figures 5 and 6 are views similar to [Figures 1 and 2 but show a modification thereof wherein the porting sleeve is of the fixed type;

Figures 7 and 8 are views of the device shown in Figures 5 and 6, but in the striking position;

Figure 9 is a transverse cross section taken on line 99 of Figure .10;

Figures 10 and 11 are views similar to Figures 5-8 and show the device thereof, but the drill is in the blowing position;

Figure 12 is a longitudinal sectional view of another modification of the drill;

Figure 13 is a view of the device of Figure 12 but in the striking position; and

Figures 14, 15 and 16 are transverse cross-sectional views taken on lines 1414, 15-15 and 1616 respectively in Figure 13.

Similar parts in the various figures will be designated with like numerals. Referring more particularly to Figures 1 to 4, the outer casing 1 forms a cylinder which is of one piece construction and extends for the substantially entire length of the tool. At the upper end of the casing a plug 2 is threadably engaged at at 3 and has an internal threaded portion 4 to which the drill string (not shown) is attachable. At the lower end of the cylinder 1 a forward sleeve 5 is inserted in the bore 6 of the cylinder and bears against a shoulder 7 at its upper end. A stop ring 8 is also inserted in bore 6 and bears against the lower end of forward sleeve 5. A locking collar 9 is threadably engaged in the lower end of the cylinder and has an upper end which bears tightly against the stop ring 8 to rigidly hold it against axial displacement. The locking collar 9 also has an internal splined portion 11 which registers with a complementary external splined portion 12 of the anvil 13 which is axially slidable within the cylinder within limits. These limits are defined in a downward direction by another spline-shaped portion 14 of the anvil which is adapted to bear against the stop ring 8 as shown in Figure 1.1. The limit of travel of the anvil in the upper direction is established by the anvil contacting the bottom rounded edge 15 of the locking collar 9, as shown in Figures 2, 4, 6, 8, 12, and 13. "A drill bit 17 is threadably engaged on the lower end of the anvil as at 18 and has a bore 19 extending therethrough which communicates with bore 20 of the anvil.

The drills shown in Figures 1-4, 12 and 13 are of the type which utilize the sliding sleeve feature of the invention while the drills of Figures 5-8, 10 and 1:1 utilize a fixed sleeve embodiment. In addition the drills shown in Figures 1-11 use a piston having a dual effective area while the drill shown in Figures 12 and 13 use a piston having a single effective area. Various combinations of these features may be incorporated as required, for example, the single eifective area piston (Figures 12; 13) could be used with a fixed sleeve arrangement (Figures -8). The difference in structure between the various devices is small and some-of the parts require only' slight modification to provide the other type. Thus common toolage'r'nay be used for many of the parts, and many are completely. interchangeable. v

Referring to the drills shown in- Figures 1- 4, a funnelshaped fluid inlet port 22 extends axially through plug 2.; A bl'ock23 is axially secured within the cylinder- 1 byth'e plug 2 which holds it against-shoulder 24 of the cylinder. Another block 25 is secured within the bore 26 of block 23 by the shaft 27 which extends through blocks 23 and 25 and holds them axially in place between the shaftshoulder 28 and the nut 29. I V t The shaft 27 includes an integrallyformed flange 3t) and a center bore 31. Cross ports 32, 33 connect the bore 31 with the annular space 35 so asto always vent space 35 to atmosphere through the center bore 36 of the piston," as will appear more fully.

A dual effective area piston or hammer 37 is used in whichthere is provided an increased amount of effective area'to which the piston is exposed during its power stroke. The piston has four circumferentially' spaced axial" grooves 38 which are interrupted by the annular flange 39 on the periphery of the piston. These grooves form distributing passages. A series of radial ports 40 extend through flange 39. The lower end of the piston also has an annular flange 41 which forms a sliding sea fit with the internal diameter of collar 5. f The terms piston, hammer? or pistonhammer will be used synonymously throughout this specification};

The dual area piston has a large central bore 42 which terminates at its front end in a wall 43 which forms a secondary effective area of the piston. The bore 42 forms a sliding seal fit with flange 30 to define a second,-

ary pressure chamber 44 to which-pressure fluid is admitted through ports 40. The primary effective area of the piston is formed by the ring 45 which is press fitted into fixed engagement with the rear end of the piston and which is slidable on shaft 27. Thus a primary pressure chamber 46 is formed to which pressure fluid admitted through the distributingpassage 38. Fluid pressure then enters ports 47 which are in communication with the annular space 48. I 1 y y A sleeve 50 is provided between the cylinder and the piston and in the embodiment of the invention shownin Figures 1-4, 12 and 13 is adapted for slight axial sliding movement within the cylinder between the positions shown in Figures 1-2 and 3- 4. The rear end of the sleeve 50 forms a sliding fit with the block 23 and block 25 and with which it defi riesthe cha'n'rber48Q Thefluid. pressure that is admitted to chamber 48 via ports 47 acts on surface 51 of the sleeve to urge the latter inf forwardor power delivering stroke simultaneously with the forward power stroke of the piston. Whehjthe sleeve: is in the position shownin Figure 3, a chamber 52 is formed between the p sleeve and block 7 25 and this chamber is always open to the atmosphere via ports The forward end of the sleeve 5 3 forms a sliding seal fit with the counterbore 55 of the cylinder. 'Ihe sleeve has an annular groove 56 formed on its internal diameter.

The'central bore 36 extendingthrough the hammer is adapted to. receive the lower end 57' of shaft 27 and is adapted to form .a sliding seal therewith as shown in Figure 1. Theend 57 thus acts as a valve element as will, appear hereinafter.

An annular space .58 is formed on the internal. surface. of cylinder 1 and receives fluid-pressure from. the t s sltq 2 1i? lt?.sirql tsu ial y...spac d.nor Thus the annular space 58 forms an inlet passage.

The operation is as follows when pressure fluid is admitted through the inlet port 22 to the inlet passage 58. The fluid then flows through the radial holes 60 in the sleeve and into the distributing passages 38 between the sleeve and piston. It then flows into the secondary chamber 44 via ports 40 and also into the primary chamber 46. From chamber .46it also flows into the sleeve actuating chambers 48 via ports 47.

,;The pressure fluid then acts on the secondary surface 43 and primary surface45; to drive the hammer 37 downwardly in the power stroke direction. At the same time the pressure fluid acts. on surfacepSl of the sleeve to drive the latter also in the downward direction.

The fluid pressure is thus effective to drive the hammer until the valve edge 62 of the hammer engages the valve edge 63 of the sleeve, thus cutting off the pressure supply to the chambers. The trapped air pressure in the chambers 44 and 46 expands and continues to drive the hammer in its power stroke until (Figure 3) the edge 64 of the hammer bore slides off the valve element 57 ofthe shaft 27 and the valve edge 65 of the rear end of the piston passes exhaust ports 33. Pressure fluid will then exhaust as indicated by the arrows in Figure 3. 7

Immediately upon the pressure being released from chambers 44 m 46, the stem or valve element 68 at the lower end of the hammer has entered the bore 20 of the anvil. Pressure fluid will flow from the inlet passage 58 via port 60 and' splined distributing passages 38 and annular groove 67 in the forward sleeve 5 to the return pressure chamber 69 and act on the lower end surface 66 of the hammer to instantaneously return the hammer to the starting position. The pressure fluid will be effective to action the hammer during the return stroke until the annular flange 41 on the lower end of the hammer passes the annular groove 67 at which time the pressure supply will be cut off to surface 66. The trapped air pressure continues to act on surface 66 asit expands and therefore continues to urge the hammer upwardly in the returndirection until the hammer valve stem 68 emerges from the bore 20.

The sleeve 50 is also returned to the starting position by pressure fluid acting on its lower edges 70, 7-1 which are greater in area than its upper edge 72. Withthe sleeve now in the upper or rearward position, the valv ing edge '62 (Figure 3) of the hammer will take a longer rearward stroke before. admitting air past the .valvingl edge 63 of the sleeve and then to the chambers 44 V With this sliding sleeve arrangement, thereforel the pressure fluid aetson the piston fora greater length of piston travel in either direction than wouldbe obtainable With a fixed sleeve. The result isa compact drill with a particularly heavy impact stroke of realtively long duration and a quick and positive return stroke which is also of longpower delivering duration. Furthermore, the double effective area of the hammer greatly in creases the impact force available. 7 The modifications shown in Figures 5 11 aregenerally similar operationto that described ab oye, but they utilize a sleeve that is fixed against axialmovement. This type of construction also results in adiametrizally compact design because it utilizes the space between the hammer and cylinder for a porting sleeve. Here, tog, the comprmsed air is carried in storage adjacenteach end of the 113111111611 With this design, however, the tim; ing of compressed air to the upper and lower ends of the drill is not. controlled quite so easily, and this design finds more utility where a lighter type impact is desirable. In the devices of Figures 5-11, it will be noted there is no sleeve actuating chamber 48, and block 74 replaces blocks 23, 25 of the Figure 1 device. Axial passages 75 and annular groove v'76 place the inlet port 22 influid against axial movement by bearing at its upper end against the shoulder 79 on block 74 and at its lower end by bearing against shoulder 80 of the casing 81. The sleeve 78 has an internal annular groove 82 intermediate its length and also has a series of radial ports 83 at its lower end which place space 58 in communication with distributing passages 38 of the hammer piston. The operation of the drill of these figures is generally the same as those of Figures 1.4, 12 and 13 except there is no movement of the sleeve. Fluid enters chambers 44 and 46 via distributing passages 38 and ports 40 and moves the hammer downwardly until ports 40 are closed by sealing against the internal diameter of the sleeve and after they have passed annular groove 82. Upon reaching the end of its downward stroke, as shown in Figure 8, fluid is admitted to the front eflective area 66 of the piston and after hammer valve element 68 has entered bore 20 of the anvil. Fluid pressure then acts on the lower end of the hammer until valve element 68 leaves the bore 20, causing the lower end to open to atmosphere.

The blowing position shown in Figures and 11 is used when it is desired to pass all of the compressed air directly through the drill and without operating the drill, for the purpose of blowing the hole completely free of drillings. This is done periodically and is accomplished as follows.

To position the various parts as shown in Figures 10, 11, it is only necessary to pull the drill slightly upwardly ofl the bottom of the hole. The piston and anvil then drop downwardly by gravityand the flange 41 (Figure 11) of the piston seals against the internal diametrical surface 6 of the forward sleeve 5. Fluid pressure then cannot reach the lower eflective area 66 of the piston hammer to return it upwardly.

When the piston is) in this position, pressure fluid is admitted past the flange 39 via the annular groove 86 cut in the internal surface of either fixed sleeve 78, or in sliding sleeve 50 of Figures 1-4. In either embodiment, the blowing feature is the same and is provided for by this blowing port 86 which permits fluid topass fully through said pressure stroke chambers when they f are open to exhaust and while the return chamber is closed. More specifically, the fluid enters the secondary chamber 44 via ports 40 and then through the bores 36, 20 and 19 out the end of the bit. Fluid also passes directly through distributing passages 38, primary chamber 46, ports 33 and out through central bores 31, 36, 20' and 19. Thus the entire pressure supply is directed freely through the drill for blowing purposes with the drill inoperative. The hammer and anvil are held in this lowermost position, not only by gravity, but also very positively by the pressure acting on the area 45 which tends to urge the piston downwardly.

The device shown in Figures 12 and 13 uses a piston having only one effective area on which pressure fluid is eflective to act in driving the piston in the power stroke direction. This simplified version of the piston has been shown with a sleeve of the sliding type but can also be used with a fixed sleeve. This piston 90 is the same as the dual area piston in regard to external size and configuration and has the annular flange 39, end flange 41 and valve element 68. With this piston construction a less heavy impact will be delivered than that delivered by the dual area type.

Various modes of carrying out the invention are contemplated as being within thescope of the following claims particularly pointing out and distinctly claiming the subject matter which is regarded as the invention.

Iclaim:

1. A fluid actuated impact tool comprising, in combination, a cylinder having a closed end and a pressure fluid inlet port adjacent to said end, an anvil slidably and sealingly mounted in the other end of said cylinder and adapted to carry a tool bit, a hammer reciprocatingly mounted within said cylinder, said hammer and anvil each having a bore extending axially therethrough, a valve stem fixedly mounted within said cylinder adjacent said closed end and adapted to receive said hammer bore in fluid sealing relationship so as to define a power stroke pressure chamber at said closed end, said hammer having a valve element adapted to enter into and form a sliding sealing fit with said anvil bore to thereby close said cylinder other end and define a return pressure chamber, a porting sleeve mounted between said hammer and said cylinder, said cylinder and said sleeve defining a fluid inlet passage therebetween which is in fluid communication with said inlet port, said sleeve and said hammer defining fluid distributing passages therebetween which are adapted to be in communication with said chambers, said sleeve having ports which place said inlet passage in communication with said distributing passage intermediate the length of the latter, and valve means between said hammer and sleeve whereby fluid is directed alternatively to each chamber to cause reciprocation of said hammer.

2. A fluid actuated impact tool comprising, in combination, a cylinder having a closed end and a pressure fluid inlet port adjacent said end, an anvil sealingly mounted in the other end of said cylinder for limited reciprocatory movement therein, said anvil having a bore extending axially therethrough, said anvil adapted to be rigidly secured to a tool bit, a hammer reciprocatingly mounted within said cylinder and having a bore extending axially therethrough and communicable with said anvil bore, a valve stem fixedly mounted in said cylinder adjacent said closed end and adapted to receive said hammer bore adjacent one end of said hammer in fluid sealing relationship so as toform a power stroke pressure chamber, said hammer having a valve element at its other end which is adapted to form a sliding sealing fit with said anvil bore to thereby form a return pressure chamber between said cylinder, hammer and anvil, a porting sleeve mounted between said hammer and said cylinder, said cylinder and said sleeve defining an axially extending fluid inlet passage in fluid communication with said inlet port, said sleeve and said hammer defining axially extending fluid distributing passages which are adapted to be in communication with said chamber, said sleeve having ports which place said inlet passage in communication with said distributing passage intermediate the length of the latter, and valve means between said hammer and sleeve whereby fluid is directed alternatively to each chamber to cause reciprocation of said hammer.

3. A fluid actuated impact tool comprising, in combination, a cylinder having a closed end and a pressure fluid inlet port adjacent said end, an anvil sealingly mounted in the other end of said cylinder for limited reciprocatory movement therein, said anvil having a bore extending axially therethrough, said anvil adapted to he rigidly secured to a tool bit, a hammer reciprocatingly mounted within said cylinder and having a bore extending axially therethrough and communicable with said anvil bore, a valve stern fixedly mounted in said cylinder adjacent said closed end and adapted to receive said hammer bore adjacent one end of said hammer in fluid sealing relationship so as to form a power stroke pressure chamber, said hammer having a valve element at its other end which is adapted to form a sliding sealing fit with said anvil bore to thereby form a return pressure chamber between I said cylinder, hammer and anvil, a porting sleeve slidably mounted between said hammer and said cylinder, said cylinder and said sleeve defining an axially extending fluid inlet passage therebetween and in fluid communication with said inlet port, said sleeve and said hammer defining axially extending fluid distributing passages, said sleeve having ports which place said inlet passage in communication with said distributing passage intermediate the length of the latter, said distributing passages adapted to be in fluid communication with said chambers, said hammer having an annular flange'on its'periphery, said sleeve 'having'aninternal annular groove registerable with; said flange tothereby form valve means between said hammer'and sleevethrough'which fluid is directed to said powerstroke chamber; and means for sliding-said-s-leevc Y in the direction of hammer movement whereby said annular flangeand groove move axially in registry to a predetermined distance.

4. A deviceas defined'in claim 3,'fu1ther characterized in that saidlast named' means in'cludes a sleeve actuating chamber in fluid receiving communication with said power stroke chamber:

5. Afluid actuated impact-tool comprising, in com bination, a cylinder having-a closed end and'a pressurefluid inlet port adjacent"said closed end, an-anvil seal ingly mounted-in 'thecth'er-Ofsaid cylinder for-limited reciprocatory movement therein,- said anvil having-a bore extending 1 axially 'therethioughi said anvil adapted to be rigidly-securedtoatool' bit, a hammer reeip'rocat-" ingly mounted Within said cylinder and having a bore 'ex-" tending axially therethrough iandcommunicable-with'said anvil bore,- a valve-stemfixedly mountedin said cylinder Y adjacent said closed end and-adapted to receive said hammer'bore adjacent'one end' of said hammer in fluid sealing relationship so as to' forma primary pressure chamber, said hammer having a'secondarypressure chamher, said hammer having a valve 'e'lementat its other end" which is adapted to enter into and foi-m'a sliding sealing fit with said anvil bore to thereby form a return'pressure chamber between said cylinder, hammer and -anvil,-said secondary chamber vented "to atmosphere via saidanvilbore when said element is not in said bore, a porting sleeve mounted between said hammer and said cylinder, said cylinder and said sleeve-defining 'an' axially extend= ing fluid inlet passage therebetween which is in fluid communication with said inlet port, said sleeve and'said hammerdefining fluid distributingpassages therebetween',

said sleeve having ports which" place said inlet passagein communiaction with said distributing-rpassage interme diate the length of the latter, fsaid distributing'passages" adapted to be in 'fluid communication with said chambers;

and valve meansbetween said hammer and sleeve whereby" fluid is directed alternatively to said primary and sec-" ondary chambers and to said .returnlchamber to cause.

reciprocation of said hammen:

6. A device as'defined 111101211111 :5, further characterized in that a chamber constantly'vented to atmosphere-is r formed in said hammer and between the :latterand the valve stem and alls'obetweensaid primary-and secondary pressure chambers."

7. A fluid actuated impact tool comprising, in com-- bination, a cylinder having a closedend and a pressure fluid inlet port adjacent said end, an 'anvil sealingly mounted in the other end of-said cylinder for limited reciprocatory movement therein, said anvil-having a bore extending axially thereth'rough, said anvil adapted to be rigidly secured -to a tool bitja hammer reciprocatingly mounted within said cylinder and having a bore extending axially therethrough and communicable with said anvil bore, a valve stem fixedly mounted in said cylinder adjacent said closedend and adapted to receive said hammer bore adjacent one end of 'said hammer in fluid sealing relationship so as to form a power stroke pressure chamher, said hammer having a valve element' at its other end which is adapted to form a sliding sealing fit' with saidianvil bore to thereby form'a' returnpressure' chamber between said cylinder, hammer and: anvil, a porting sleeve mounted betweensaid hammer and-said. cylinder, said cylinder andsaid sleeve defining an axially extending fluid inlet passage therebetween in fluid communication witlis'aid' inletport said sleeve and said-hammer definingaxially extending fluid distributing passages 'therebetwe'en, said sleeve ha-vingports which place saidiinlet passage'in 'j connnunication with said distributing passage intermediate -the length of the latter, said distributing'passages 2 adapted to be in fluid communication with said charnport.

binationyla 'cylinder having' aclosed end' and a pressure fluid inlet porhadjacent thereto; an anvil slidably and. sealingly mounted'inthe other end of said cylinder and:

adapted; to carry a tool bit, a hammer reciprocatingly "mounted-"within said cylinder, said hammer and anvil each having a bore extending axially therethrough; a

valve stem fixed-ly *mounted within said cylinder adjacentfsaidclosed endand' adapted'to receive said hammer bore fluid sealingrelationship-soasto form a primary pressure chamber, said hammerhavinga secondary pres: sure chamber,"said hammer-havinga valve element. adapted toenterinto and form' a sliding sealing fit .vvith said-anvil'boretothereby form "a return pressure. 0113111 her, said secondary-chamber vented"to"atmosph erefvia* 35 said anvil bore when said element is notinsaid bore,-a

porting-sleeveslidably=mounted between said hammer 1' and said cylinder, said cylinder and said sleeve defining a fluid inlet passage therebetwe'en-"and in fluid communication with saidinlet'port, said sleeve and said hammer defining a fluid distributing passage'therebetween which is adapted to be in communication with said: chambers,

said sleeve having ports which connect-said inlet and:

distributing passages intermediate the length" of the" latter,

saidhammerhaving an annular flange-on its-periphery, said sleeve havingan internal annular 'groove 'registerable I with said'flange-to thereby form valve means' between said-hammer and sleeve through-Which fluid'is directed to saidprimary andsecondary chambers, and'mans for" sliding said sleeve in thedirection ofhammermovement whereby-said annular flange -an'd groove moveaxially' in registry for a predetermined distance 9. A device as defined in claim-8, further characterized I in that said hammer-hasa second annularperipheralflange cooperable with an annul'a'r' 'groove at the' forward end of said cylinder forming valve means throughwhich fluidis directed to the end of said hammer:

References Cited intthe file of this patent UNITED STATES PATENTS" 1,053,304 Le Gendre Feb. 18,1913 1,345,270 i Smith's June 29,- 1920 1,499,569; Bailly 1 July 1, 1924 1,692,937 Hulshizer Nov. 27,1928 2,333,405 Appton a Nov. 2,1943 2,661,928'- Topenaliar Dec. 8,1953 2,665,115 Bassinger Ian: 5,1954 2,810,549 Morrison Oct. 21, 1957 2,851,251 Mori Sept. 9, 1958 8. A fluid actuated impact tool comprising, in=com- 

